The ethidium cation of the salt ethidium bromide has been previously shown by others to be a sequence specific nucleic acid intercalating agent. We have covalently linked the ethidium cation to agarose gel beads through a spacer arm to produce an affinity chromatography system for nucleic acid. The interaction of the gel bound ethidium ion into nucleic acid double helices has been demonstrated by a variety of biophysical techniques including fluorescence. Preliminary experiments indicate that crude transfer ribonucleic acid can be fractionated to some degree on this column using elution with a linear sodium chloride gradient.